The invention relates to electric lamps comprising a tubular lamp vessel sealed in a vacuum-tight manner and having respective seals at opposite ends thereof, an electric element disposed in said lamp vessel, first and second current-supply conductors extending axially from said electric element through said seals to the exterior of said lamp vessel, and a lamp base disposed on each seal comprised of a conductive contact connected to the respective current-supply conductor and an electrically insulative sleeve in which said contact is mounted.
Lamps of this type are known from U.S. Pat. No. 3,001,096 (Moseby) and U.S. Pat. No. 4,404,491 (Siaens et al). The lamp bases carried by the opposing seals are of the R7 type and cooperate with spaced sockets to support the lamp in a fixture. The conductive contacts have an outer face of concave spherical contour which mate with opposed rounded probe-like terminals of the spaced sockets. When used in a fixture with a reflector, the socket terminals cooperate with the contacts to align the electric element of the lamp with the focus of the reflector. The contacts are recessed in the insulative sleeve to prevent persons from touching the contacts when the lamp is secured in electrically live sockets.
In the known lamps, the conductive contacts are first aligned with and welded to the respective current-supply conductor. The insulative sleeve is then mounted over the conductor and secured to the seal by basing cement or by a metal spring connected to the conductive contact. The application and curing of cement is time consuming and hence expensive, and also of low mechanical strength. The use of a metallic spring is also unfavorable because it increases the number of lamp parts and increases lamp cost.
It is the object of the invention to provide a lamp of the type described in the opening paragraph in which the sleeve and conductive contact are secured in a more cost effective and reliable manner.